The internet and other networks have greatly enhanced the ability of individuals to communicate. Among the communication tools that utilize these networks are instant messaging services. Instant messaging services enable users to communicate with each other via real time or quasi-real time exchange of text and images. Like other communication media, however, instant messaging services are prone to abuse by advertisers and other purveyors of undesirable or inappropriate content. One example of such content is commonly known as “spam”, which refers generally to unsolicited bulk messages sent over electronic communication media. In the context of instant messages services, spam is also referred to as “SPIM”, or “spam over instant (or internet) messaging.” Individuals and entities that transmit SPIM and other inappropriate or undesirable content are commonly known as “spimmers”. The abuse of instant messaging services by spimmers ties up valuable network bandwidth and degrades the overall user experience for legitimate instant messaging users. While various techniques have been implemented to stem the spread of SPIM, the problem persists.